Studies On Width To Thickness Ratio Limitation Of High Strength(Q460) Equal-leg Angle Members Under Axial Compression

In common steel members under axial compression,we usually uses the method of limiting board width to thickness ratio to control that the local buckling critical stress of board biger or equal to the integral buckling critical stress of the bar.It could ensure that we can designing structure in the base of integral buckling capacity of the steel bar. However,our national Code for Design of Steel Structures(GB50017-2003)only have the specific provisions of the board width to thickness ratio for the Q235,Q345,Q390, Q420,and not include the Q460.In addition,it also has a weakness that how to deal with when the width to thickness ratio limitation surpasses the limitation of the standard.It's necessary to take test calibration for the rationality of the formula of the code.Theoretical analyzing,testing and FEM calculating are included in this paper to study the local buckling and width to thickness ratio limitation of high strength angle to axial compression.According to the principle of"Equal Stability",the Width to Thickness ratio limitation of the angle with the assumption that local buckling does not occur before integral buckling in an element is deduced.To verify the rationality of the theoretical deduction,axial compression test and related material test have been adopted in the Structure and Resistance Earthquake Laboratory of Xi'an University of Architecture & Technology.The tset include 16 groups that divided into 4 different sections(L125×8,L125×10,L160×l0,L160×l2)with each section having 4 varied slendemess(λ=30,λ=45,λ=60,λ=80),and each group having 3 members.Finally FEM analyses 8 different representative sections of Hot rolling equal-angle iron size, contour,weight and allowable deviation(GB9787-88).Corresponding conclusions have been drawn. By testing and FEM analyzing,the revision of the Width to Thickness ratio limitation in the new version Code is not rational for using of the high strength steel,it's slightly strict.It should be modified appropriately.this paper suggested the following equation for the revision in thedomestic Code for Design of Steel Structures (GB50017-2003):b/t≤0.95×(5.5+0.14λ)(30≤λ≤100)whereλ-slenderness ratio of the larger value between the two axis.